The present invention relates to a power supply, particularly, to a power supply capable of outputting multiple voltages.
An electrical equipment such as laser printer is normally provided with a power supply that converts AC voltage supplied from an external commercial power supply to DC voltage. Also, the laser printer is provided with a motor and logic circuit, where each of them is driven respectively by a different voltage. Accordingly, the power supply often can supply multiple voltages.
An example of a conventional power supply that outputs multiple voltages as described above is disclosed in Japanese Patent Application Publication No. 2000-14141. This power supply performs a feedback control wherein an amount of current flowing in a primary side of a transformer is controlled based on a voltage of a secondary side of the transformer.
However, the cost of the device increases if the feedback control is performed for each of the multiple voltages. Japanese Patent Application Publication No. 2000-14141 performs the feedback control only for high voltage and generates lower voltage from the high voltage using a DC-DC converter.
However, Japanese Patent Application Publication No. 2000-14141 also causes increase of cost since the device has multiple DC-DC converters.